Add class QgsComposerRuler
Add composer rulers to composer graphics view
Implement drawing of ruler markers
Fix ruler layout
Don't draw view frame (alignment with ruler widgets)
Fix calculation of ruler y-coordinates
Read composer from xml considers rulers
Better placement for y-coordinate labels
Show ruler marker for cursor position
Store reference to composition in ruler to get page info
Consider multiple pages for ruler scale
Improve coordinate display
Show snap lines in ruler mouse move event
Snap to arbitrary snap lines
Improve handling of snap lines
Implement moving of snapped features together with the snap line
[Atlas] Fix UI to be consistent with the use of QgsCollapsibleWidgets
[Atlas] Update spacing for atlas panel
Fix #6184, canvas doesn't refresh after pasting layer style
Replace saving done dialog with message bar